The basic theories of operation and construction of tuning fork gyroscopes are now fairly well known. Such gyroscopes include a substrate, silicon proof masses with comb electrodes, position sensitive pick-offs, sense electrodes, and inner and outer drives with comb electrodes. The proof masses are suspended above the substrate by a support flexure which permits movement of the proof masses relative to the sense electrode, the drive electrodes and the substrate.
The substrate, which is commonly constructed from glass, has a high electrical resistivity which is partially responsible for voltage transients which can adversely effect gyroscope performance. In particular, coupling between comb electrodes is sensitive to such voltage transients. Additionally, the transients impart undesirable vertical (Z-axis) forces normal to the proof masses and pick-off sensitivity. This vertical force and pick-off sensitivity can (a) degrade tuning fork gyroscope performance and (b) prevent the tuning fork gyroscope motor self-oscillator loop from starting.
It is known in the art to attempt to alleviate these problems by shortening the comb electrodes of both the drives and proof masses. However, this technique has at least one potential drawback. Shortening the comb electrodes limits maximum drive amplitude because the combs disengage so that the drive force becomes small. As such, the performance of the tuning fork gyroscope may be adversely affected.